The present invention relates to keycaps for computer keyboards, electronic typewriters, data entry units, and other similar apparatus. In particular this invention provides a number of varied height keycaps that when placed on a standard QWERTY keyboard positions the fingers and hands in an ergonomic position. The keycaps are positioned on the keyboard in such a manner that they form an inverted V or wave shape. The keycaps on the far left of the keyboard are generally shorter, with keycaps getting higher towards the center, and then shorter towards the right side of the keyboard.
The present invention places the hands a more natural hand and arm position when typing and thereby reduces repetitive stress injuries (RSI) such as carpal tunnel syndrome (CTS), flexor tendinitis, extensor tendinitis, and DeQuervain's disease.
Frequent use of a conventional horizontal keyboard results in injuries due to the unnatural angle the hands are required to assume to operate the keyboard when typing. An operator of a conventional horizontal keyboard must rotate his arms so as to dispose his hands are in a palms-down position, by pronation, and align his fingers with the rows of keys by twisting each hand outward at the wrist, by ulnar deviation. Conventional horizontal keyboards result in the operator's arm and hand muscles operating outside their natural and ideal range, and thus functioning poorly and increasing risks of injury. Tendons and nerves are adversely affected and over time this abuse can lead to repetitive stress injuries. For example, an operator of a conventional horizontal keyboard often types with bent wrists, resulting in irritation and bunching of the sheaths surrounding the tendons. This bunching affects the sensitive median nerve in the carpal tunnel, and may lead to carpal tunnel syndrome (CTS). Symptoms of CTS are "shooting" pains from the wrists to the forearms, palms or fingers. In extreme cases, CTS and other RSI are permanently debilitating. In a significant number of cases, repetitive stress injuries force keyboard operators or other workers which frequently use a keyboard to an alternative type of employment that does not require use of a keyboard.
Computer keyboard injuries annually afflict about 185,000 office and factory workers and cost companies about $20 million. Presently, annual worker's compensation payments for these injuries is approximately $1.1 billion. The competitive advantages of data processing indicate that computer use, and therefore the number, frequency and cost of repetitive stress injuries due to conventional keyboards, is certain to increase. Over the last decade the number of employees using conventional computer keyboards in the United States has increased from approximately 5 million to 50 million. In total, there are presently about 120 million keyboard operators in the United States. To reduce the occurrence of CTS and other repetitive stress injuries, a keyboard should alleviate the underlying causes of repetitive stress injuries.
Such an improved keyboard, which is realized in the present invention, must relieve muscle and tendon strain, lessen or reduce wrist deviation, reduce or eliminate forearm pronation, reduce the distance fingers must travel and lessen the force necessary to the keys. Dr. David Thompson, a professor emeritus at Stanford University has found that muscles worked less with hands typing on an angled keyboard on a 30 degree tilt and significantly less with a 60 degree tilt. Dr. Thompson stated that it took about 40 percent more muscle effort to type on a flat linear keyboard than on a keyboard with a 60 degree tilt. Additionally, muscles worked less with straight wrists than when the wrists are bent. Dr. Thompson explained that the harder muscles work the more likely they are to become overworked and this increases the possibility the user will become fatigued, as well as the likelihood that repetitive stress injuries may occur.
A number of prior art keyboard designs have been proposed in an attempt to reduce RSI. This is seen in, for example, U.S. Pat. Nos. 4,378,553 to McCall and 4,661,005 to Lahr, which disclose a design where the conventional QWERTY keyboard layout is split into two separate pieces, allowing the operator to space each horizontal keypad at a comfortable interval. Other designs angle a horizontal planar keyboard into a V shape or chevron design as illustrated by U.S. Pat. Nos. 5,156,475 to Zilberman and 5,129,747 to Hutchison. Other designs split the keyboard and rotate each split half of the keypad into a vertical position as disclosed in U.S. Pat. Nos. 5,160,919 to Mohler and 5,137,384 to Spencer. These designs purport to reduce wrist deviation and hand pronation.
U.S. Pat. No. 4,597,681 to Hodges discloses an "Adjustable Keyboard" divided into two sets of keys that are adjustable relative to each other in both a horizontal and vertical manner. FIGS. 3 and 4 of Hodges indicates that the split keyboard may be pivotally adjusted to form an inverted V. Another keyboard design is disclosed in U.S. Pat. No 5,067,834 to Szmand which discloses an "Input Keyboard Apparatus for Information Processing Device and Other Keyboard Devices." The input keyboard of Szmand includes a left and right keyboard each mounted on a telescopic shaft attached to a base support plate. The two keyboards form a generally inverted V shaped spacing with each keyboard having a front-to-back inclination and a lateral side inclination with universal pivots permitting individual settings for an operator. The keyboard connecting pivot unit is releasable to allow lateral spacing of the keyboard.
Snap on keys have been used in prior art. This is seen in, for example, U.S. Pat. No. 4,755,072 to Hoornweg, which discloses removable transparent colored key caps for color coding a keyboard. These colored transparent keycaps fit over the keys of a keyboard enabling a subset of keys to be distinguished by color while maintaining visibility of the key designation. All the keys of Hoorneg's design of are of uniform height. U.S. Pat. No. 5,183,346 to Tesar discloses a similar design. Tesar uses snap on keys to convert symbols on a computer keyboard to another set of graphic symbols. This is used with computer software programs that enable the an operator to type in a number of different languages. Rather than replacing the keyboard, snap on keycaps specific to a one particular language will be placed on the data entry keys of the keyboard of another language. For example, snap on keycaps showing the graphic symbols of the Thai language may be placed over the computer keyboard that comes standard with English keycaps. Once again all the keys of Tesar's design are uniform or the same height.
No prior art designs use a variety of different height keycaps to convert a horizontal keyboard into an ergonomic keyboard. Rather the keyboard must be redesigned. As there are approximately 120 million horizontal computer keyboards in the U.S. a simple, cheap and efficient method or transforming existing horizontal keyboard into an ergonomic keyboard is developed in the present invention through the use of snap on ergonomic keycaps. Consequently, the benefits of these designs can be obtained without having to purchase a new redesigned computer keyboard.